Multi-Protocol Label Switching (MPLS) Label Distribution Protocol (LDP) enables peer label switch routers (LSRs) in an MPLS network to exchange label binding information for supporting hop-by-hop forwarding in an MPLS network. Within the context of next generation multicast virtual private networks (NG-MVPNs), to receive a multicast traffic over a MPLS/LDP transport tunnel at a leaf node, Protocol Independent Multicast (PIM) follows Reverse Path Forwarding (RPF) procedures and programs <source, group> (S, G) records with indices which represent the transport tunnel on which traffic is expected. For a given (S, G) record at a leaf node, RPF indices determine which transport tunnel interfaces are going to be used in order to receive traffic.
In current Selective Provider Multicast Service Interface (S-PMSI) implementations for NG-MVPNs with MPLS as transport, each of the SG records at a leaf node for a path (S,G) belonging to a single MVPN stores the following data: (1) Root PE's I-PMSI index as RPF-Primary index; (2) Root PE's S-PMSI index as RPF-Secondary index; and (3) the Rendezvous Point's (RP's) I-PMSI as RPF-RP index. This data, which is stored in three RPF indices at the leaf node, helps in lossless SPT switch from (*, G), lossless transition from I-PMSI to S-PMSI and vice versa.
In current Source Redundancy implementations for NG-MVPNs with MPLS as transport, each of the SG records at a leaf node for a path (S,G) belonging to a single MVPN stores the following data: (1) I-PMSI Index from Primary Source as RPF-Primary index; (2) I-PMSI Index from Secondary Source as RPF-Secondary index; and (3) RP PE's I-PMSI as RPF-RP index. This data, which is stored in three RPF indices at the leaf node, helps in providing a fast switch from a Primary Source Tunnel to a Secondary Source Tunnel in case of Primary Tunnel failure, thereby minimizing the traffic loss at the leaf node.
To implement Source Redundancy with the context of the selective provider multicast service interface (S-PMSI) Model, the above implementations are used together, which requires that five indices be maintained and programmed in order to achieve the benefits of both the models; namely, (1) inclusive provider multicast service interface (I-PMSI) Index from the primary source; (2) S-PMSI Index from the primary source; (3) I-PMSI Index from the secondary source; (4) S-PMSI Index from the secondary source; and (5) I-PMSI index from the RP. This implementation is very expensive and undesirable from both a data plane perspective and a control plane perspective.